The break-up has left Hollywood abuzz but hardly surprised: Nikki Finke is leaving Deadline.com, the entertainment news site she founded, after months of public bickering with the owner.

The grand dame of film and celebrity journalism is to set up a new venture after a failed, final effort to make peace with her employer, the media mogul Jay Penske, it was confirmed on Wednesday.

“Despite attempts by all to have it go otherwise, Nikki Finke will no longer be leading Deadline Hollywood, and she will not be writing weekend box office or filing stories going forward,” the site reported. “This is an emotional and painful parting of the ways for us.”

It said the site would never completely replace “Nikki's unique voice” but would hire new staff and move forward. “Businesses evolve and change, and we’ve learned that no one is indispensable.”

Finke, 60, a self-described "bitch", has been called Hollywood's most powerful and uncompromising journalist, and announced her departure in a typically combative tweet:

Jay Penske has just told me I am free to leave. He tried to buy my silence. No sale.

She said she would build NikkiFinke.com into a new must-visit site for Hollywood. “There. Will. Be. Blood,” she tweeted, directing readers to a page with an invitation and warning: “Come for the cynicism. Stay for the subversion. Don't steal Nikki's scoops.”

Deadline evolved from Finke's blog and drew fans with scoops, reputation-shredding attacks on industry figures and "live snarking" commentaries during award ceremonies. She sold it to Penkse in 2009, reportedly for $14m, and stayed on as editor despite warnings of a rocky relationship.

The collaboration soured last year after Penske bought Variety, a once-mighty industry magazine weakened by online rivals such as Deadline. He refused to give Finke a role in the revamped Variety and she accused him of starving Deadline of resources, prompting Finke to take repeated “vacations” and potshots at her employer.

He had made a once-feared site “bland and boring” and tried to muzzle her with legal letters, she told the Guardian last month. "I will not be harassed and I will not be intimidated by the company that employs me.”